Recirculating
systems

In a recirculating system the nutrient solution is pumped from a reservoir
to the plantís roots. The excess nutrient is then allowed to drain back to
the same reservoir (Fig 1.1). This permits reuse of the nutrient
solution
until it is either depleted of useful elements or is contaminated. The
nutrient solution is then discarded and replaced with fresh nutrient.

There are several types of recirculating
systems in use. The most popular types are: